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To get the Greates Common Factor (GCF) of 630 and 342 we need to factor each value first and then we choose all the copies of factors and multiply them:
|630: ||2||3||3||5||7|| |
|342: ||2||3||3|| || ||19|
|GCF: ||2||3||3|| || || |
The Greates Common Factor (GCF) is: 2 x 3 x 3 = 18